Various types of bulbs have been used initially as a light source for a lamp of a vehicle, but recently, a light emitting diode (LED), which has excellent light conversion efficiency and a low amount of heat radiation, may be reduced in size and weight, and has a long lifespan, has been widely used as a light source.
In general, the LED has an advantage in that a color temperature of the LED is about 5,500 K, which is close to a color temperature of sunlight, so as to greatly reduce eye strain that causes fatigue, and the LED has an advantage in that a size of the LED is small so as to increase a degree of design freedom when a lamp for a vehicle is designed.
An LED array is a type of light source formed by mounting a plurality of LEDs, and may directly produce various beam patterns by selectively turning on the plurality of LEDs. For this reason, the LED array may be applied to a head lamp and a rear lamp of a vehicle so as to be effectively used to produce various beam patterns.
The lamp for a vehicle may be configured by installing an aspherical lens in front of the LED array, and light passing through a focal point of the aspherical lens travels straight after passing through the aspherical lens. There is a characteristic in that when the focal point is positioned on an optical axis, the light passing through the aspherical lens travels straight parallel to the optical axis.
FIG. 1 is a photograph illustrating a lighting image of a lamp for a vehicle which uses an LED array as a light source, and uses an aspherical lens.
Considering a characteristic of the LED array in which a plurality of LEDs is typically disposed to be aligned in a predetermined direction, there is a problem in that an amount of light in an A region illustrated in FIG. 1, that is, a front region and a light width region of the vehicle is not sufficient, and the front region and the light width region become dark.
FIG. 2 is a view illustrating a low beam region of a general lamp for a vehicle, in accordance with an isolux curve, and FIG. 3 is a view illustrating a low beam region of a lamp for a vehicle which uses an LED array as a light source, in accordance with an isolux curve.
When comparing an isolux curve (5 lux) 1, which shows a low beam region of a general lamp for a vehicle as illustrated in FIG. 2, with an isolux curve (5 lux) 1, which shows a low beam region of a lamp for a vehicle which uses an LED array as a light source as illustrated in FIG. 3, it can be seen that an amount of light in a short distance region and a light width region 2 of a vehicle 10 is insufficient for the latter rather than the former.
As a result, there is a problem in that in a case in which an auxiliary light is not present, it is difficult for the lamp for a vehicle, which uses the LED array as a light source, to produce a low beam at night.